Those are independent releases. As far as I know there is no collaboration between tdragon and MinGW; other than tdragon is a member of the MinGW developer community.

Quoted from the link you point to:

The TDM-GCC builds are unofficially created packages designed to replace, for experimentation purposes, the official MinGW releases of GCC binaries. The TDM-GCC builds typically contain fewer changes from the vanilla sources and receive less testing than their official counterparts. Since these builds are not formally affiliated with or endorsed by the MinGW project, they should be treated as unstable and unsupported software -- in other words, use it at your own risk.

herr-master, what do you think MinGW-NNN.exe means? It doesn't mean literally MinGW-NNN.exe; NNN is a place holder for the current version number, and at the time you posted your comment, that was 5.1.4, (so representing the MinGW-5.1.4.exe you saw -- thus, there is nothing to be fixed, beyond a minor clarification of this).

Today, when I click through the link above, I see a large green button bearing the legend "Download Now!" and pointing to MinGW-5.1.6.exe, which is exactly as it should be; (NNN has now become 5.1.6).

If you want other packages, beyond the default base system which MinGW-NNN.exe will install, then you need to click through the files link, or the smaller white button, bearing the legend "View all files".